diff --git a/app/src/main/java/app/revanced/integrations/sponsorblock/StringRef.java b/app/src/main/java/app/revanced/integrations/sponsorblock/StringRef.java
index 71ed866b..14f1a201 100644
--- a/app/src/main/java/app/revanced/integrations/sponsorblock/StringRef.java
+++ b/app/src/main/java/app/revanced/integrations/sponsorblock/StringRef.java
@@ -5,16 +5,20 @@ import android.content.res.Resources;
 
 import androidx.annotation.NonNull;
 
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.Map;
 
 import app.revanced.integrations.utils.LogHelper;
 import app.revanced.integrations.utils.ReVancedUtils;
 
+// should probably move this class into utils package
 public class StringRef {
     private static Resources resources;
     private static String packageName;
 
-    private static final HashMap<String, StringRef> strings = new HashMap<>();
+    // must use a thread safe map, as this class is used both on and off the main thread
+    private static final Map<String, StringRef> strings = Collections.synchronizedMap(new HashMap());
 
     /**
      * Gets strings reference from shared collection or creates if not exists yet,
@@ -90,9 +94,11 @@ public class StringRef {
     @NonNull
     public String toString() {
         if (!resolved) {
-            Context context = ReVancedUtils.getContext();
-            resources = context.getResources();
-            packageName = context.getPackageName();
+            if (resources == null || packageName == null) {
+                Context context = ReVancedUtils.getContext();
+                resources = context.getResources();
+                packageName = context.getPackageName();
+            }
             resolved = true;
             if (resources != null) {
                 final int identifier = resources.getIdentifier(value, "string", packageName);